The United States healthcare system is identified as being the worst of sixteen industrial nations with regard to amenable mortality,3 ranks poorly on access and safety,4 and rewards quantity of services delivered at the expense of higher quality care.2 The patient-centered medical home (PCMH) is considered a delivery system innovation for improving health in the United States22 and is a cornerstone of current health care reform efforts.4-7 The success of reform efforts will be measured primarily across the three domains of the Triple Aim framework: simultaneously 1) enhancing patient experiences of care and 2) improving population health while 3) reducing health care costs.38 The success of the PCMH to achieve the Triple Aim is dependent on the delivery of treatments and interventions with demonstrated effectiveness (i.e., evidence-based practice (EBPs)). Effective use of EBPs in the PCMH is contingent on a supportive climate in the organization.14-15 However, the extent to which the organizational climate in the PCMH supports or impedes EBPs is unknown. This mixed- methods study will assess EBP implementation climate (i.e., the extent to which organizational members perceive that the adoption of EBPs is expected, supported, and rewarded) and attitudes about EBPs in the PCMH. This study will do so in two practices, one that has achieved recognition as an NCQA Level 3 certified PCMH (PCMH), and another that plans to transform into a PCMH (non- PCMH). Additionally, this study will assess potential changes in EBP implementation climate and attitudes about EBPs over time within these two practices. Understanding the climate for EBP implementation in the PCMH and non-PCMH practices over time will help in informing the development of strategies to promote EBPs, further serving to accelerate PCMH transformation toward achieving the Triple Aim. The proposed research study is an excellent fit with the AHRQ's Mission and Research Priority Area #1: Improve health care quality by accelerating implementation of patient centered outcomes research (PCOR). Specifically, results from this proposal will guide the development and utilization of interventions designed to improve health and healthcare quality by accelerating the sustainable implementation of EBPs in the PCMH.